1748. Interrelationship of Weight and Cost Reduction


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J W Turner: 1748. Interrelationship of Weight and Cost Reduction. 1986.



At Bell Helicopter TEXTRON, Inc. during early preliminary design of a helicopter or VSTOL aircraft, a Design-to-Cost (DTC) program is implemented and a DTC team is formed. The objective of DTC is to establish life cycle cost as a technical parameter, equal in importance to performance and schedule considerations in the development of a new or modified aircraft. The team utilizes computerized DTC models that contain various cost estimating relationships (CERs) to project the aircraft unit production cost. These CERs include weight sensitive parameters and are based on early design concepts. The resulting DTC estimate is used as a tool to track cost and influence design decisions. As preliminary design transitions into full-scale development (FSD), parametric cost estimates are replaced with more detailed grass roots estimates. At the same time, increasing emphasis is placed on weight reduction. To provide visibility for the importance of weight reduction, BHTI management introduces a Weight Improvement Program (WIP). This program rewards employees for submitting weight reduction ideas that are incorporated into FSD and/or production aircraft. Management of cost control parallel to weight reduction is a design challenge. When a WIP suggestion is submitted, review is solicited from all engineering disciplines. As verified by previous correlation studies, decreases in weight often correspond to decreases in cost. This correlation is the cornerstone of most parametric CER models. However, at the detail level, care must be taken to ensure that WIP proposals are carefully examined for cost ramifications. WIP proposals that result in development or production cost increases have significant negative impact on a contractor in the current fixed price contract environment. A timely question is: What is the value of a pound of weight saved? This paper describes the methodology that was developed and currently used by Bell Cost Analysis Engineering to review WIP proposals. Based on this methodology, the DTC Team recommends approval or disapproval of WIP suggestions to management. An example is used to illustrate the implementation of the value-per-pound methodology.


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